Anode array techniques

ABSTRACT

A multianode array is formed by prefusing thin sheaths of glass to Kovar rods and stacking the sheathed rods together with glass cane. The structure is then fused to form a continuous matrix by processing under high temperature and pneumatic pressure to form a solid billet from which anode stems are sliced for use with photomultipliers and other varied components.

United States Patent [56] References Cited UNITED STATES PATENTS2,608,722 9/1952 Stuetzer 29/592 3,206,831 9/1965 Strother 29/5723,319,318 5/1967 Taimuty 29/592 3,204,326 9/1965 Gamay": 29/419 X3,562,894 2/1971 Rome 29/412 Primary Examiner-John F. Campbell AssistantExaminer-Robert W. Church Attorneys-Harry A. Herbert, Jr. and Ruth G.Codier ABSTRACT: A multianode array is formed by prefusing thin sheathsof glass to Kovar rods and stacking the sheathed rods together withglass cane. The structure is then fused to form a continuous matrix byprocessing under high temperature and pneumatic pressure to form a solidbillet from which anode stems are sliced for use with photomultipliersand other varied components.

slsaslzvo PATENTEIJ JAN! 1 me 000000 O0 0 0000000 oooooooooo INVENTOR.BAG DASAR DERADOOR IAN ATTORNEYS ANODE ARRAY TECHNIQUES BACKGROUND OFTHE INVENTION This invention relates to anode array techniques and moreparticularly to the formation of anode bundles from which anode stemsmay be sliced.

There are a number of applications where it would be highly desirable touse a matrix photomultiplier tube having a multianode array elementtherein. For instance, in laser radar tracking a matrix detector willprovide both range and azimuth information and it will also dividesignal-obscuring background radiation associated with a large totalsensitive area down to a small amount of background radiation in eachdetector.

Another quite different type of situation arises in extracting all theinformation inherently available from an image being observed with anastronomical telescope. It is well known that in practice the detailobtained from such images is limited not by diffraction but byatmospheric turbulence. Since photographic emulsions lack sensitivity,they integrate the atmospheric turbulence over sustained periods of timewhich blurs the image. However, a matrix photomultiplier is highlysensitive; and if the signals at all anodes are recorded, it is possibleby subsequent signal processing to compensate for the turbulence usingimage reconstruction techniques.

A matrix photomultiplier is also analogous to a highly sensitive eye inthe sense that visible images are converted into a large number ofparallel electrical signals. The time is approaching when integratedcircuit techniques will be sufficiently advanced to permit sophisticatedpattern recognition using electronic logic circuits to simulate nervoussystems.

The problem is to provide within a single envelope many individualphotomultipliers, each of which operate independently with a minimum ofcross-coupling. At the same time, the high sensitivity aNd widebandwidth characteristics of photomultipliers must be preserved.

From the above, it is clear that the key to the design of a matrixphotomultiplier is an electron multiplier element capable of highspatial resolution, high gain, fast response, and simple construction.This requires the inclusion of a multianode stem which maintains vacuumintegrity and is compatible with phototube materials and processes.

SUMMARY OF THE INVENTION In response to the needs noted above, a processwas evolved wherein anodes are arranged in a parallel array, as forexample in a 10 XIO geometric formation, using glass tubing and cane inthe interstitial areas, and compacting at a sufficiently hightemperature with pneumatic pressure to fuse the discrete parts into asolid matrix containing, in the 10 l array, a hundred separate andparallel anodes.

The object of the invention is, therefore, to provide a method ofproducing a multianode array for use in a photomultiplier tube elementin laser radar detectors or the like wherein the array of anode elementsare of the proper density to receive the information while being ofspecified center-to-center spacing and overall dimensions.

Another object of the invention is to provide a method of producing amultianode stem wherein a plurality of Kovar rods are positioned in aX10 array within a matrix of glass to form a billet from which a waferis cut and polished.

A further object of the invention is the provision of a multianode stemwherein the cross-coupling capacitance between the elements iscontrollable to within the limits specified.

A still further object of the invention is to provide a multianode stemwhich maintains vacuum integrity after prolonged use in a matrixphotomultiplier or the like.

Another still further object of the invention is to provide a method offabricating a multianode stem which produces a finished product that iscompatible with phototube materials and processes presently available.

These and other advantages, features and objects of the invention willbecome more apparent from the following description taken in connectionwith the illustrative cmb0di ment in the accompanying drawing.

DESCRIPTION OF THE DRAWING In the drawing:

FIG. 1 is a view illustrating the steps involved in the process, andshowing also one form of the billet;

FIG. 2 is a cross section taken substantially on the line 2-2 of FIG. 1;

FIG. 3 is a view of a 10 X10 anode stem arrangement; and

FIG. 4 is a section of an anode stem taken on the line 44 of FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT The complete anode stemdesignated generally by the reference numeral 10 is shown in FIGS. 3 and4 consists of individual anodes 12 within a borosilicate glass matrix14. The anodes are arrayed in a square geometry, 10 to a row.

The assembly and processing techniques that permitted the constructionof this array are as follows:

In the process of developing a method which would realize the objectivesas above stated, glass tubing 16 and glass cane rods 18 and 20 arestacked together into a matrix of approximately 1 -inch by 1 -inchformat. The size of the glass cane was selected to fill the intersticesand to provide the calculated spacing between the anode wires 12.Thereafter anode wires 12 of approximately 0.030-inch diameter, andwhich later formed the pins of the completed anodes, were threadedthrough the tubing 16. The billet 22 was formed by assembling thestacked matrix inside a glass tube 24 and vacuum fused by feeding slowlythrough an oven at approximate softening temperatures, and thereafterannealed. The fused and annealed billet was sliced into wafers andpolished to produce the completed anode stem, an example of which isshown in FIGS. 3 and 4.

Outer leads 26 were supplied as necessary to provide the necessaryexternal connections to the input and output of the multianode array 10.

In a subsequently developed process, Koval wire was used for the anodematerial 12. Before drawing the wire through the glass tubing 16, thinsheaths of glass were applied to the Kovar rods by a prefusing process.In this method also, the cane l8 and 20 and the sheathed Kovar rods werearranged to achieve a 10 l0 array. The bundle thus formed was insertedinto glass tube of Coming No. 7052 type. The bundle was then vacuumfused by feeding the anode matrix structure slowly through an oven wherethe separate glass rods, tubes and sheathing are fused into a solidmatrix surrounding the Kovar rods. After annealing, the billet is slicedand polished as desired, and the completed anode stems shown in FIGS. 3and 4 are obtained.

Although the invention has been described with reference to a particularembodiment it will be understood to those skilled in the art that theinvention is capable of a variety of alternative embodiments within thespirit and scope of the appended claims.

lclaim:

I. The method of producing a vacuumtight multianode stem structure foruse in a photomultiplier component, said process comprising the steps ofprefusing a thin sheath of glass around an anode wire, inserting thesheathed anode wire into a closefitting glass tube, stacking said anodewire into an array with glass cane and tubing in the interstitials toform an anode matrix structure of a desired design, inserting thestacked anode matrix structure into a glass tube, vacuum fusing theanode matrix structure by feeding slowly through an oven at softeningtemperature to form a billet, annealing said billet, and slicing saidbillet to form a wafer, grinding and polishing said wafer to form amultianode stem.

2. The method of producing a multianode stem defined in claim 1 whereinthe anode wire is Kovar.

3. The method of producing a multianode stem defined in claim I theglass cane and tubing in the interstitials is glass.

4. The method of producing a multianode stem defined in claim 1 whereinthe anode wires are stacked in a X10 geometric pattern to form a 100-anode array.

1. The method of producing a vacuumtight multianode stem structure foruse in a photomultiplier component, said process comprising the steps ofprefusing a thin sheath of glass around an anode wire, inserting thesheathed anode wire into a closefitting glass tube, stacking said anodewire into an array with glass cane and tubing in the interstitials toform an anode matrix structure of a desired design, inserting thestacked anode matrix structure into a glass tube, vacuum fusing theanode matrix structure by feeding slowly through an oven at softeningtemperature to form a billet, annealing said billet, and slicing saidbillet to form a wafer, grinding and polishing said wafer to form amultianode stem.
 2. The method of producing a multianode stem defined inclaim 1 wherein the anode wire is Kovar.
 3. The method of producing amultianode stem defined in claim 1 the glass cane and tubing in theinterstitials is glass.
 4. The method of producing a multianode stemdefined in claim 1 wherein the anode wires are stacked in a 10 X 10geometric pattern to form a 100 -anode array.